Solar clock displaying the hour by the projection of the shadow of the sun, even on cloudy days, day and night

摘要

A screen (1) marked in hours (2) may be rotated by 30 deg about a vertical axis and receives a shadow (4) from a gnomon (3). The gnomon is suspended by four upper strings (5-8) and four lower strings (9-12). The upper strings are actuated by motors on a pivoted platform (17) fixed to a sliding beam (18) and the lower strings by motors on a sliding trolley (20,21). All the motors are controlled by a sensor of sun direction